On day of event online tickets sales are shut off about 3 hours before event or when sold out. Most times walk-up tickets are still available.

Time listed on Cannon Battle Ticket is when boarding check-in ends:

If you check-in after that time you miss the boat, and that would be sad. For Cannon Battles, we suggest checking-in at least 15 minutes before your ticket time, to allow time to get checked in. You can check-in as early as 9am.